敌百亩和阿米津的太赫兹透射光谱研究

为获得敌百亩和阿米津两种农药在太赫兹频段内的光学参数,完善常用农药太赫兹光谱数据库,利用太赫兹时域光谱技术(THz-TDS),在室温294 K和氮气环境(湿度小于4%)下,对两种农药标准样品进行测试。获得了两种农药的太赫兹时域信号,并利用傅里叶变换和菲涅尔公式得到0.3~1.5 THz频段内的折射率谱和吸收谱。结果表明,敌百亩和阿米津的平均折射率分别为1.59和1.55,敌百亩吸收谱有3个吸收峰,阿米津有2个吸收峰,且两者吸收峰的位置与峰值存在明显的差异。相对于阿米津,敌百亩对于太赫兹波有更好的吸收特性。试验光谱特征说明,利用THz-TDS可以实现对农药的检测与鉴别。

Transmission spectra research into Dibam and Simazine in terahertz region

This paper is engaged in a transmission spectra research into Dibam and Simazine in terahertz region.For our research purpose,we have measured two kinds of pesticides,i.e.Dibam and Simazine,by means of terahertz time-domain spectroscopy(THz-TDS),to obtain the absorption spectra and refractive spectra in hoping to improve the fingerprint data base of pesticides.The above said measurement was conducted at the room temperature(294 K),with the measuring space filled with nitrogen to reduce the concentration of vapor.While the measuring condition is likely to lead to the increase of the experiment noise,the humidity has also to be controlled within 4%.In addition to the time domain signals of dibam and simazine given by THz-TDS,there also exist problems of amplitude reduction and time delay when compared with the reference signal.We have also gained the frequency domain signals,and worked out the absorption coefficient and refractive index from 0.3 THz to 1.5 THz by using the model,which was put forward based on Fresnel equation via the fast Fourier transform(FFT).Besides,we also found that dibam has three absorption peaks while simazine has two,which is characteristic of the structure of the pesticide molecules.The results of our experiments prove that the average refractive indexes of Dibam and Simazine are 1.59 and 1.55.THz wave,which has low energy,can supply rich molecular data,due to strong the intermolecular and great intra-molecular vibration,showing that THz-TDS can be used for identifying other materials.As a kind of bactericide for disinfection,dibam helps to prevent botanic disease and insect pests for its pathogenic microorganism,whereas amazine,a kind of herbicide,enjoys low mammalian toxicity and can therefore be used for removing weeds in the corn fields and garden running.Moreover,since THz-TDS is a promising nondestructive means for low frequency molecular vibration spectra,it can be used for the chemical substance identification and quantitative analysis,therefore useful for safety detection,medicine analysis and food safety.In short,the experiment results we have gained here can be used as reference to measuring pesticide residues in farm production.